This invention relates to dental bonding and more particularly to a dental adhesive material in the form of a sheet of semi-rigid, self-sustaining adhesive material sandwiched between two layers of backing material for use in bonding a dental inlay or a crown to a dental surface.
Dental bonding materials are prevalently utilized throughout the field of dentistry for securing crowns and restorative material onto dental surfaces. Numerous types of bonding materials are readily available including various composites, glass ionomers, and other chemicals which have been suggested. All of these are generally in the form of a paste or liquid which is typically applied onto the prosthesis and then the prosthesis pressed onto the dental surface. In utilizing such bonding materials, because of the fluid nature of the adhesive, it is not possible to obtain a uniform thickness of application between the inlay or a crown and the dental surface. This can cause an uneveness and frequently may shift the theoretical placement of the inlay from its actual desired locations on the dental surface.
Additionally, since the adhesive is generally in a liquid or paste state, there may be voids in the application of the adhesive on the inlay and the voids remain between the inlay and the dental surface. This may cause decay in the voids as well as disturbing the retention of the dental inlay.
Additionally, with the use of the adhesive liquid or paste bonding material, the material may squeeze out beyond the dental inlay and it is a difficult procedure to remove the adhesive and achieve a proper seal at the boundary between the inlay and the dental surface. This is even further complicated when the marginal edge occurs at the gum interface where adequate trimming and shaping of edges becomes difficult.
The problem of utilizing a paste or liquid is even further compounded in connection with aesthetic dentistry in which veniers are applied onto cut-down dental enamel. In this procedure, the existing enamel is initially reduced by minimal thicknesses, and typically, a porcelain inlay is then produced to seat into the reduced area of the enamel. Very thin layers of adhesive are needed to apply the inlay. With the use of existing adhesive pastes or liquids, voids are generally found in the interface. Likewise, when utilizing liquid or paste bonding material, the paste is applied onto the porcelain inlay and then the inlay pressed onto the dental surface. There is a shifting that may occur between the inlay and the dental surface in trying to position the inlay properly. Additionally, because of the uneven placement of the adhesive, as the adhesive squeezes out beyond the inlay there may be an uneven accumulation on one side of the tooth more than the other side causing inter-tooth spacing to be uneven.
This problem is even more compounded in the use of a porcelain inlay for posterior teeth. In order to permit adequate fit, the inlay is usually oversized to accommodate the adhesive material. As the application of the inlay occurs, shifting of the inlay causes uneven interspacing between adjacent teeth.
In addition to the problems resulting from utilization of the liquid or paste bonding materials, frequently there is also a problem of adequate retention with such material. While bonding materials being developed continue to provide improved retention capabilities, these are limited to chemical bonding capabilities. Little, if any, attention has been given to mechanical bonding in conjunction with the chemical bonding.
Further problems with existing bonding chemical agents concern the accurate placement of the dental prosthetic. By way of example, in the case of placement of a porcelain inlay, while the enamel of the dental surface may have been cut down, there may still be movement while placing of the inlay and accurate positioning is often difficult. Suitable physical mating structure would be helpful to provide accurate placement of the inlay without interfering with the proper adhesion and securement of the inlay.
Additional problems occur in connection with the placement of a peripheral crown about a cut-down tooth. Typically, a profile is formed about the tooth on which the crown will fit. Existing arrangements often cause difficulty in proper seating of the crown, especially at the lower edge meeting the gum line where a feathering effect occurs at the rather sharp edge of the crown which can bite into the gum line. Especially with existing bonding agents, there is a tendency to slide or shifting of the crown on the tooth surface which can cause cutting into the gum. Likewise, existing bonding agents fail to provide any mechanical bonding but rely exclusively on the chemical bonding effect of the material.
Accordingly, while there continues to be development in the field of bonding agents, further improvement in the bonding arrangements of a dental inlay onto a dental surface appears to be appropriate.